2012-2013 :2m BAC

1

S , M1 M2 d=M1M2=3,4cm =100s .1- V1 .2- (echographie), V2=1500m/s : - V1 V2 . - t t=20s. L S .

2

20KHz v=340m/s1- (0,5) = 83kHz N t=36ms 2- T .3- K . 4- =20ms . d .5- V=36Km/h . N=8KHz air=4,25cm eau=18, 75cm6 7 .

3

20KHz . 1- .2- . E R1 R2 E . R1 R2. R1 R2 Y1 Y2 ( 1). 6.10-6 s/div R1 R2 4cm R1 R2 . R1 R2 R2 R1 6,55cm 3- R1 R2 4- T R1 R2 N 5- Vair 6- R1 5,02cm H=15,3m . . Vair m/s Veau=1500. . h . A xA=0m B =50m xB (3). t

( 4) A , . 20ms/div7- 8- t A . 9- h t H Veau Vair.10- (5) t=f(x) t x A B x.

4

(1) R1 R2 d. (2) d1=41cm. : 0,1ms/div1-1- R2 1-2 N .1-3- R2 R1 R2 d2=61,5cm .2- =-d1 d2 .

1GBF01020304050607080dR1()R2022 2div- V .- R1 R22 - R2 , R1 R2 92.25cm=d32-1 - d1=(k-n) + / 2 d3 n k , K>n 2-2 2 R1 R23- a=7cm ,